GB2233118A

GB2233118A - Vehicle braking control

Info

Publication number: GB2233118A
Application number: GB9000732A
Authority: GB
Inventors: Geoffrey Dennis Miller; Clas Kemstedt
Original assignee: E B SIGNAL; M L ENGINEERING; E B Signal A B; Ericsson Signal Systems AB
Current assignee: E B SIGNAL; M L ENGINEERING; E B Signal A B; Ericsson Signal Systems AB
Priority date: 1989-01-13
Filing date: 1990-01-12
Publication date: 1991-01-02
Anticipated expiration: 2010-01-12
Also published as: GB2233118B; GB9000732D0; GB8900774D0

Abstract

A vehicle 1 constrained to travel along a pathway 2, for example a train, is brought to a desired velocity (eg zero) at any advanced position 10. Knowing the velocity of the vehicle 1 at its present position 4, an automatic control system estimates the maximum velocity achievable at locations between the present position 4 and the advanced position 10 (eg from track gradient data) and determines an intermediate position 7 at which a service brake should be applied. If the actual velocity exceeds a calculated maximum allowable velocity at any position between the intermediate and advanced positions 7 and 10, an emergency brake is automatically applied. The maximum allowable velocities may be calculated by the control system from track gradient data and the braking characteristics of the vehicle in question. <IMAGE>

Description

Vehicle Movement Control This invention relates to controlling automatically movement of a vehicle constrained to travel along a predetermined pathway, and is especially, but not exclusively, applicable to the automatic and emergency control of a travelling railway vehicle.

According to the invention, we provide a method of controlling automatically movement of a vehicle constrained to travel along a predetermined pathway in such a way that, at a position of the vehicle at any given instant (hereinafter referred to as "the present position"), the vehicle can be caused to be travelling at a desired velocity when at an advanced position on the pathway ahead of said present position, which method comprises the automatically effected steps of monitoring the actual velocity of the vehicle at said present position and estimating the maximum achievable velocity of the vehicle at each of a plurality of positions between said present position and said advanced position using predetermined maximum achievable levels of acceleration for the vehicle at velocities differing from one another; determining a position of the vehicle intermediate said present and advanced positions at which a service brake should be applied in order to reduce the velocity of the vehicle from the maximum achievable velocity at said intermediate position to the desired velocity at the advanced position; calculating, for each of a plurality of positions between the intermediate and advanced positions, the maximum allowable velocity of the vehicle at that position if said service brake is to reduce the velocity of the vehicle to the desired velocity at the advanced position; and, if the actual velocity of the vehicle exceeds the calculated maximum allowable velocity of the vehicle at any one of said plurality of positions between the intermediate and advanced positions, applying sufficient emergency braking force to the vehicle to reduce the velocity of the vehicle to the desired velocity at the advanced position.

Preferably, application of said service brake of the vehicle when the vehicle is at said intermediate position in order to reduce the velocity of the vehicle from the maximum achievable velocity at said intermediate position to the desired velocity at the advanced position is effected manually by the driver of the vehicle but, in some cases., it may be desirable for the service brake to be automatically applied when the vehicle is at the intermediate position.

With the former case in mind, preferably the method also includes the automatically effected steps of calculating the time at which it is estimated the vehicle will reach the calculated maximum allowable velocity at any one or more than one of the plurality of positions between the intermediate and advanced positions; and activating an audible and/or visible alarm at at least one predetermined time in advance of said calculated time to alert the driver that the service brake is to be applied.

The method of the invention can be arranged to accommodate for the worst possible situation, namely the situation when the vehicle accelerates at its maximum achievable level of acceleration between said present position and said intermediate position when the service brake is applied. The maximum allowable velocity of the vehicle can be conveniently calculated taking into account the reaction time for the service brake to be applied and assuming the vehicle accelerates at its maximum achievable level of acceleration between said present and intermediate positions.

The desired velocity of the vehicle at said advanced position may be zero, such as may be required in the event of an obstruction ahead of the vehicle, or it may be a predetermined maximum velocity, such as may be required where, for safety reasons, a speed restriction is necessary on that part of the predetermined pathway.

Preferably, the steps of the method are automatically effected under the control of at least one computer.

The method preferably further includes the automatically effected steps of determining, from an indication of the gradient of the predetermined pathway between said present position of the vehicle and the advanced position, the effect of the gradient on the maximum achievable velocity of the vehicle at each of said plurality of positions between said present and advanced positions and, having regard to said determination, appropriately modifying determination of the intermediate position at which the service brake should be applied. In this way, calculation of the possible acceleration of the vehicle will take into account any uphill or downhill gradient of the predetermined pathway.

Alternatively or additionally, the method may further include the automatically effected steps of determining, from an indication of the gradient of the predetermined pathway between the intermediate and advanced positions, the effect of the gradient on the maximum allowable velocity of the vehicle at each of said plurality of positions between the intermediate and advanced positions and, having regard to said determination, appropriately modifying calculation of the maximum allowable velocity of the vehicle at each of said plurality of positions. Thus, the effect of the gradient of the predetermined pathway on the braking characteristics of the vehicle can also be taken into account when calculating the maximum allowable velocity of the vehicle at each of said plurality of positions.

To enable information concerning the gradient of the predetermined pathway at positions spaced along the length of the pathway ahead of the vehicle to be taken into account, preferably such information is stored in the computer in a memory and/or is fed into the computer of the vehicle from ground-based equipment at positions spaced along the route of the predetermined pathway.To accommodate for vehicles having braking characteristics differing from one another, information concerning the gradients of the predetermined pathway appropriate to vehicles having braking characteristics differing from one another may be stored in and/or fed into the computer, the gradient information appropriate to any particular vehicle being selected by computing apparatus of the vehicle for use in determination of the intermediate position and/or calculation of the maximum allowable velocity of the vehicle at each of said plurality of positions between the intermediate and advanced positions.

The invention is further illustrated by a description, by way of example, of the preferred method of controlling automatically movement of a railway train constrained to travel along a railway track with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of a railway train travelling along a section of railway track, and Figure 2 is a distance/velocity graph illustrating the steps automatically effected to control movement of the railway train along the section of railway track shown in Figure 1.

Referring to the drawings, an electrically driven railway train 1 is travelling along a section of a railway track 2 at a velocity of u mph and it is required to bring the train to a standstill at an advanced position 10 on the track to avoid collision with a preceding train. Using computing equipment, at the present position 4 of the train the actual velocity of the train is monitored and the maximum achievable velocity of the train at each of a plurality of positions between the present position 4 and the advanced position 10 is estimated having regard to predetermined maximum achievable levels of acceleration for the train at velocities differing from one another and having regard to the effect of the gradient of the track between the present position 4 and the advanced position 10. A position 7 on the track 2 intermediate the present position 4 and the advanced position 10 is determined at which a service brake should be applied to the train in order to reduce the velocity of the train from the maximum achievable velocity at the intermediate position 7 to zero at the advanced position 10. For each of a plurality of positions between the intermediate position 7 and the advanced position 10, the maximum allowable velocity of the train at that position if the service brake is to reduce the velocity of the train to zero at the advanced position 10 is calculated taking into account the effect of the gradient of the track between the intermediate position 7 and the advanced position 10 on the maximum allowable velocity of the train at that position.

The gradient information used by the computing equipment of the train in determination of the intermediate position and/or calculation of the maximum allowable velocity of the train at each of the plurality of positions between the intermediate and advanced positions may be stored in the computing equipment in a memory and/or may be fed into the equipment from ground-based apparatus at positions spaced along the route of the railway track. The computing equipment of the train will select from gradient information which is appropriate to trains having braking characteristics differing from one another and which is stored in and/or fed into the equipment, the particular gradient information appropriate to the train on which the computing equipment is carried.

The time at which it is estimated the train will reach the calculated maximum allowable velocity at any one or more than one of the plurality of positions between the intermediate position 7 and the advanced position 10 is automatically calculated and an audible and visible alarm is activated at a predetermined time in advance of this calculated time to alert the driver to apply the service brake of the train in order to reduce the velocity of the train from the maximum achievable velocity at the intermediate position to zero at the advanced position 10. If, during passage of the train from the intermediate position 7 to the advanced position 10, the actual velocity of the train exceeds the calculated maximum allowable velocity of the train at any one of the plurality of positions between the intermediate position 7 and the advanced position 10, an emergency brake of the train is automatically applied to ensure that the velocity of the train is reduced to zero at the advanced position 10.

Claims

1. A method of controlling automatically movement of a vehicle constrained to travel along a predetermined pathway in such a way that, at the present position of the vehicle as hereinbefore defined, the vehicle can be caused to be travelling at a desired velocity when at an advanced position on the pathway ahead of said present position, which method comprises the automatically effected steps of monitoring the actual velocity of the vehicle at said present position and estimating the maximum achievable velocity of the vehicle at each of a plurality of positions between said present position and said advanced position using predetermined maximum achievable levels of acceleration for the vehicle at velocities differing from one another; determining a position of the vehicle intermediate said present and advanced positions at which a service brake should be applied in order to reduce the velocity of the vehicle from the maximum achievable velocity at said intermediate position to the desired velocity at the advanced position; calculating, for each of a plurality of positions between the intermediate and advanced positions, the maximum allowable velocity of the vehicle at that position if said service brake is to reduce the velocity of the vehicle to the desired velocity at the advanced position; and, if the actual velocity of the vehicle exceeds the calculated maximum allowable velocity of the vehicle at any one of said plurality of positions between the intermediate and advanced positions, applying sufficient emergency braking force to the vehicle to reduce the velocity of the vehicle to the desired velocity at the advanced position.

2. A method as claimed in Claim 1, wherein application of the service brake of the vehicle when the vehicle is at said intermediate position in order to reduce the velocity of the vehicle from the maximum achievable velocity at said intermediate position to the desired velocity at the advanced position is effected manually by the driver of the vehicle.

3. A method as claimed in Claim 2, which method also includes the automatically effected steps of calculating the time at which it is estimated the vehicle will reach the calculated maximum allowable velocity at any one or more than one of the plurality of positions between the intermediate and advanced positions; and activating an audible and/or visible alarm at at least one predetermined time in advance of said calculated time to alert the driver that the service brake is to be applied.

4. A method as claimed in any one of the preceding Claims, wherein the desired velocity of the vehicle at said advanced position is zero.

5. A method as claimed in any one of the preceding Claims, wherein the steps of the method are automatically effected under the control of at least one computer.

6. A method as claimed in any one of Claims 1 to 4, which method further includes the automatically effected steps of determining, from an indication of the gradient of the predetermined pathway between said present position of the vehicle and the advanced position, the effect of the gradient on the maximum achievable velocity of the vehicle at each of said plurality of positions between said present and advanced positions and, having regard to said determination, appropriately modifying determination of the intermediate position at which the service brake should be applied.

7. A method as claimed in any one of Claims 1 to 4 and 6, which method also includes the automatically effected steps of determining, from an indication of the gradient of the predetermined pathway between the intermediate and advanced positions, the effect of the gradient on the maximum allowable velocity of the vehicle at each of said plurality of positions between the intermediate and advanced positions and, having regard to said determination, appropriately modifying calculation of the maximum allowable velocity of the vehicle at each of said plurality of positions.

8. A method as claimed in Claim 6 or 7, wherein the steps of the method are automatically effected under the control of at least one computer.

9. A method as claimed in Claim 8, wherein information concerning the gradient of the predetermined pathway at positions spaced along the length of the pathway is stored in the computer in a memory and/or is fed into the computer of the vehicle from ground-based equipment at positions spaced along the route of the predetermined pathway.

10. A method as claimed in Claim 9, wherein information concerning the gradients of the predetermined pathway appropriate to vehicles having braking characteristics differing from one another are stored in and/or are fed into the computer, the gradient information appropriate to any particular vehicle being selected by computing apparatus of the vehicle for use in determination of the intermediate position and/or calculation of the maximum allowable velocity of the vehicle at each of said plurality of positions between the intermediate and advanced positions.

11. A method of controlling automatically movement of a railway train constrained to travel along a railway track substantially as hereinbefore described with reference to the accompanying drawings.